Rock drilling head

ABSTRACT

A rock drilling head ( 1 ) with a drilling diameter (D) between 25 mm and 60 mm and formed of no more than five separate parts, has at least one rinsing channel ( 2 ) formed in the outer surface ( 3 ) of the drilling head and expanding from the outer surface ( 3 ) inward in form of a nozzle, the rinsing channel having a diameter (S) amounting to between 1/20 and ⅕ of the drilling diameter (D).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rock drilling head provided with hard material means and having rinsing channels and designed for use, in particular, in blast shot drills or injection self-drilling anchors.

2. Description of the Prior Art

Such mass-produced drilling heads, to which the present invention is limited, have, at a drilling diameter between 25 mm and 60 mm, a small degree of complexity. So the number of separate parts, such as hard material inserts that form cutters, is limited, for manufacturing reasons, to a small number, maximum five. Dependent on the type of a to-be-drilled underground, these rock drilling heads are operated in a wet drilling process with low (5 to 30 bar) water pressures or in a dry drilling process with aspiration of drillings (with suction pressure 0.3 to 0.7 bar), with the rinsing or suction taking place through the rinsing channels having a rinsing channel diameter between 1/20 and ⅕ of the drilling diameter.

U.S. Pat. No. 4,185,708 discloses such a rock drilling head equipped with hard material cutter means and having cylindrical rinsing channels formed directly of the drilling head base body and having different channel diameters.

U.S. Pat. No. 4,540,056 discloses a rock drilling head equipped with hard material cutter means with a drilling diameter of 2.5 cm replaceably secured in head support in which special high pressure nozzles, which are formed as screw-in inserts, are screwed in cylindrical openings. The opening diameter of the high-pressure nozzles is too narrow to provide for removal of drillings at a dry drilling or to obtain, at wet drilling with a low water pressure, a necessary rinsing medium flow.

An object of the present invention is to provide a rock drilling head equipped with hard material cutter means, having a drilling diameter between 25 mm and 60 mm, rinsing channels suitable for both wet and dry drilling, and suitable for mass production.

SUMMARY OF THE INVENTION

This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a rock drilling head having a drilling diameter between 25 mm and 60 mm formed of no more than five separate parts and including at least one rinsing channel formed in the outer surface of the drilling head and expanding from the outer surface inward in the form of a nozzle, and having a diameter(s) amounting to between 1/20 and ⅕ of the drilling diameter.

With a rinsing channel that constantly expands inwardly in the form of a nozzle (along the flow and having a concave, conical, or convex profile and being, in flow cross-section, rotationally symmetrical, completely symmetrical, and asymmetrical), the drillings, which are aspirated from outside in the rinsing channel in the dry drilling process, cannot be detained there because the cross-section of the rinsing channel constantly widens inward. During wet drilling with low-pressure rinsing means, with the flow directed from the interior outwardly, a high flow velocity is achieved in the narrowing outer region of the rinsing channel, and the drillings, which are accumulated in the rinsing channel, are subjected to the dynamic pressure of the rinsing medium flow and are carried along.

Advantageously, the rinsing channel expands from the outer surface with a cone angle between 3° and 30°, which ensures a sufficiently large widening of the cross-section inwardly.

Advantageously, there are provided two rinsing channels which are advantageously arranged symmetrically with respect to the drilling axis, so that with blocking of one of the rinsing channels, at least one other rinsing channel is available.

Advantageously, the rock drilling head is formed of a base member formed as a casting, with the rinsing channel being advantageously formed during casting.

Advantageously, the rock drilling head is formed of only one base member and only one hard material insert extending diametrically over the drilling diameter and secured in a groove formed in the one base member. This ensures an economical production of the rock drilling head with few process steps.

The novel features of the present invention which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiment, when read with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings show:

FIG. 1 a longitudinal cross-sectional view of a rock drilling head according to the present invention along line I-I in FIG. 2 in three planes; and

FIG. 2 a plan view of the rock drilling head according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A drilling head 1 for a rock drill, which is shown in FIGS. 1-2, has drilling diameter D of 35 mm and two rinsing channels 2 located on opposite sides of a drilling head axis A. The rinsing channels 2 have a rinsing channel diameter S at an outer surface 3 and equal to about 1/10 of the drilling diameter D. The rinsing channels 2 expand conically inward from the outer surface 3 in form of a nozzle with a cone angle α of 20° that constantly diminishes further inward. The drilling head 1 is formed of exactly two separate parts, a base member 4 of steel cashing and a hard material insert 5 secured in a groove 6 of the base member 4. The hard material insert 5 extends diametrically over the drilling diameter D and forms drilling cutters 7,

Though the present invention was shown and described with references to the preferred embodiment, such is merely illustrative of the present invention and is not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiment or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims. 

1. A rock drilling head having a drilling diameter (D) between 25 mm and 60 mm and formed of no more than five separate parts, comprising an outer surface (3); and at least one rinsing channel (2) formed in the outer surface (3) and expanding from the outer surface (3) inward in form of a nozzle, and having a diameter (S) amounting to between 1/20 and ⅕ of the drilling diameter (D).
 2. A rock drilling head according to claim 1, wherein the rinsing channel (2) expands with a cone angle (α) between 3° and 30°.
 3. A rock drilling head according to claim 1, comprising a further rinsing channel (2).
 4. A rock drilling head according to claim 1, comprising a base member (4).
 5. A rock drilling head according to claim 4, wherein the base member (4) is formed as a steel casting.
 6. A rock drilling head according to claim 4, further comprising a hard material insert (5) extending diametrically over the drilling diameter (D) and secured in a groove (6) formed in the base member (4).
 7. A rock drilling head according to claim 1, comprising only one base member (4), and only one hard material insert (5) extending diametrically over the drilling diameter (D) and secured in a groove (6) formed in the one base member (4). 